1. Field
The invention relates to a hand-operated, portable, soil working apparatus wherein the soil engaging assembly rotates about an axis disposed substantially normal to the soil surface.
2. Prior Art
Various soil tilling implements are available for cultivating, mulching, weeding, digging holes, etc., ranging from tractor powered implements for working large farm acreages to individual manually-operated and powered hand tools, the least of which includes the shovel, hoe, post hole digger and pick. As well known to all farmers, weekend gardeners, homeowners, etc., a great deal of physical effort is required when utilizing the latter, soil working hand tools.
Accordingly, the development of light-weight, portable, hand-held soil working tools, which require less expenditure of energy by an operator while increasing his productivity, was inevitable. Typical of such individual tools are powered soil tillers such as those known by the term "rototillers", and exemplified generally by the description and drawings of U.S. Pat. Nos. 2,614,474 and 2,634,666 to C. Merry; 2,871,585 to A. Merry et al.; 3,559,743 to P. Hastings; 3,559,744 to J. Olinger; 3,734,201 to R. Zaun; 3,739,856 to C. Ray; 3,779,320 to N. Cantone; and 3,794,123 to J. Whitesides.
Such implements successfully accomplish the basic soil tilling operation, but are relatively large, rather unwieldy devices, with a plurality of radially extending tines secured to a shaft which rotates about a horizontal axis. The larger tillers may include devices mounted on a tractor for working farm acreages, or may include gas engine powered devices on wheels such as those commonly available in tool rental shops, and/or used by gardeners or homeowners for tilling garden plots, lawn areas, etc., about the average home or industrial complex. In such tillers, the large contact area of the vertically turning radial tines must be forced into the soil as they sequentially rotate against it along an arcuate path. If the soil is hard, interspersed with rocks or pebbles, is clayey, or otherwise consolidated, it is very difficult to provide sufficient force to maintain the large area tines in the soil, particularly in the case of the smaller, hand operated implements. If follows that the efficient working of only friable soil is practical unless the soil has been thoroughly watered or otherwise softened or broken-up prior to the tilling operation.
In addition, most of the above tillers discussed and exemplified in the patents are bulky and unwieldy, and are used for working generally open plots of land rather than for close tilling, cultivating or weeding in established flower beds, ground cover areas, and other planted areas. Likewise, the tillers cannot be readily used to work any plots of land, whether pre-planted or not, wherein there is any appreciable slope, and definitely are unuseable on hillsides of 15.degree. or steeper slopes.
Recently a smaller, hand-held, wheel-less tiller has been introduced which also rotates about a horizontal axis and is designed for tilling smaller plots of land with an improved degree of versatility and portability. Such a hand-held powered tool may be used between larger plants, shrubs, trees, etc. However, since it employs the radially extending tines about a rotating, horizontal shaft, the device cannot be readily forced into any unwieldy soil by the single operator; ergo, it is primarily useful for cultivating relatively soft and yielding soil in areas where there is sufficient room for the width and diameter of the rotating tines to clear all protruding shrubbery or plants.
Another related type of soil tiller is available where the soil working tines are of various geometries, and unlike the previous prior art tillers are arranged generally vertically, for rotation about a vertically oriented axis. Typical of these devices are those which perform various soil working functions as described in U.S. Pat. Nos. 2,888,084 to F. Trecker; 1,578,769 to N. Sergeant; 2,625,867 to W. Hands, Jr.; 3,667,551, 4,029,153, 4,034,814, 4,042,041 to C. van der Lely; 3,774,688 and 3,821,989 to A. van der Lely. In the above applications, the soil working harrow or cultivator implements are primarily on wheels and/or are tractor mounted for use in tilling large acreages. The implements employ a plurality of pairs of tines, each pair rotatable about a vertical axis, wherein the combination is adapted via a tractor mounted frame to cultivate or work a swath of soil with one pass of the tractor. The rotating pairs of soil working tines are forced into and maintained within the soil by the weight of the tractor and implement and the structural rigidity of the implement frame.
The concepts of the above tillers wherein the soil working members rotate about a vertical axis, have been further adapted to hand-held, powered, soil working implements as described in U.S. Pat. Nos. 2,888,084 to F. Trecker and 4,003,436 to P. Foster et al. The hand-held device of 2,888,084 is used for light tilling of small plots of land, but must utilize a dragging vertical fin to control the rotating tines while working across the soil surface. The device of 4,003,436 employs two pair of vertical tine structures which are purposely powered for opposed oscillation about respective vertical axes, not for continuous rotation thereabout. The tine pairs are oscillated in opposed directions via a complicated linkage/cam drive train in order to prevent the implement from "walking" over the surface of any but the softest soil. The hand-held versions of U.S. Pat. Nos. 2,888,084 and 4,003,436 employing rotating or oscillating tines, cannot be forced into or maintained in soft or hard soil by a single operator, if only a single pair of tines are employed or if no adjunct dragging fin is used. Even when using opposing pairs of tines and/or adjunct dragging vertical fins, such tillers still tend to "walk" across the surface of the soil.